Portable load lifter



Dec- 8, 1953 H. J. HULsART PORTABLE LOAD LIFTER 2 Sheets-Sheet 1 Filed Aug. 14. 1950 INVENTOR ATTORNEYS.

Patented Dec. 8, 10953 UNITED STATES PATENT OFFICE PORTABLE LOAD` LIFTER Harold. J. Hulsart, Tuscaloosa, Ala. Applcaton'August 14, 1950, SerialfNo. 179,217 s claims. (c1. .2m-.1m

This invention relates to a portable load. lifter adapted to elevate a load; of. any type of material to a desired extent, 'forI any of the variouspurposes, as for instance, stacking.,v machine feeding, off bearing', andlthe like.

The primary purpose of' theV invention is. tov providev a portable and. low cost. lifting: device of conveniently4 low overall. height, having a platform or load lifting carriage capable of being lowered' completely to the ioor, thus to permit loading of said platform with. rolling: material handling equipment;

Another important object is to provide a devicey of the character described which isf so constructed as to distribute' a lifting force applied. at one; end

.thereof equally beneath both ends of the platforni in a mannerv to elevate' the load a selected distance, with the. apparatus accomplishing this result. while still retaining the lowered'. height. of the platform and lifting. mechanismv on at least three sides thereof within small' dimensional limits, thus: to permit handling of overhanging. stoel; suchv as plywood loadedon; pallets, skids, or oor'trucks.

Another' important. object is to: construct a load lifting device as described wherein lifting. effort' will be in dire'ct'proportionto the load.

Still another important. object is' to provide load lifting device of the character described that be. of simple construction, without thenecesl sity of constructing the same with abase or special; chassis, the devicel being so formed astoc'om- Aprise essentialy no morev than a platform or carriage, and supporting legs and; associated power means.

Still another obiect. is Yto mountY the casters or wheels, which make the device portable,l on the legsl of the apparatus in such a wayV as to causez said casters or Wheels to support the lifterY while in. an elevated position and to automatically permit retraction to lowered position for rolling of a: material handling truck or the like onto' the platform.

Withthe foregoing and other objects in viewV which will appear as the description proceeds, the invention consists of certain novel details of construction and combinations of parts, hereinafter morer fully described and pointed out in the claims, it being understood that changes may be made in the construction and arrangement of parts without departing from the spirit of the invention as claimed.

Referring. tothe drawings Fig.v l isa side eleva-tion of one form ofthe nvention in an elevated position. Y

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Fig. 2 is an elevation taken from thev rig-ht of Fig; 1- on a reduced scale.

Fig. 3 is. an enlarged fragmentary vertical. sectional view through the connection betweena a feed screwvv and. toggle.

Fig. 4 is a side elevation of a modified form, a' load of' material' being illustrated on saidv modi'- iied form. Y

Fig. 5 isa.v view similar to Fig. 4, the load being reduced? somewhat and the load lifter being elevated a distance necessary t'o make up for the re-f duction in the load siz'e.

Referring tothe drawings'indetail, the form of the invention as illustrated inA Figs'. 1 to 3 in elusive I provide at opposite Sides of the lifting device inclined legs I extending from front to rear of theY device and provided at their free ends with casters 2` supported upon the' floor' or other supporting surface S.

Intermediate their ends, the legs I are respectively pvotally joined' as at` 3 to other legsl 4 equipped with the casters 5.

In the loweredposition of thelifter, the legs Il and 4- are adapted to extend horizontally inv 1ongitudinal contactwith each other, thusk to permit lowering of the platform 5 fully to floor level. Inthis connection, the platform 5 isY provided with the raised side walls 6`the top edges of. which are provided' with the outturned longitudinal flanges 1f.

The upper or inner' end' of the legs Il are pivot'ally connected to the side walls 6 at a point'. abovethe planeof the-platform 5, by pivot pins 8".

The upper ends of the legs 4'1ar'e: connected., by pivotal connec'tionsy 9', kto' the frontv portions ofthe side walls 6,. alsoabove. the plane of the platform` 52. thev pivot pins 9' passing through4 slotsv I0 formed in` saidl sidewalls.

Rigidly securedv to the rear' edge of the plat` form 5 and extended transverselyv thereof. is an inverted. channel member' I I, and carried by the channel member I I adjacentiopposite' endsi thereof are trunnions I2' toY which are pi-votally connected', the upper ends of.v toggle links I3 also disposed transversely of the platform.

At their other' ends, the links lf3 are pivotally connected asl at I4 to sleeves I15 havingA the in-y ternally threaded bores I6 in which is engagedv a' screw Il having right and left hand threads asbest seen: from Fig. 2. A

The pivotal connections I'Ilalso connect to the sleeves andi t'o the' toggle links I3`- lower toggle links` I8,v which are pi'votally joined at theirlower endsto trunnions |191 carriedby a channel memloer 2li adgacent" opposite ends thereof. Thisl channel member is fixed at opposite ends to the legs 5 adjacent the lower ends thereof and extends transversely of the load lifter beneath the channel member l l.

A motor supporting platform 2i is provided wi-th the forwardly extended hinge brackets 22, that are pivotally hung upon the smooth intermediate portion of the screw il. As a result the motor support 2l is itself swingably mounted upon the feed screw.

A motor 23 is mounted upon the support 2l, and drives the small drive sprocket 24 around which passes the chain E5 driving the larger driven sprocket 2S secured to the feed screw Il for the purpose of rotating said feed screw.

In use, it will be understood that the device can be lowered to a point at which the base of the platform is hat upon the floor or other supporting surface S. Since three sides of the carriage or elevatable platform are small dimensioned and are completely clear of the power source, loads can be placed upon said platform from any of these three sides, and in addition, can overhang all three sides as desired.

When the load is to be elevated, the motor 23 is switched on, and will cause rotation of the feed screw. As a result, the sleeves i5 are fed longitudinally of the screw in opposite directions, actuating the toggle links i3, and i8 in a manner to elevate the load supporting platform that comprises the platform base 5 and the side walls 6.

Of importance, in this connection, is the fact that in any position to which the platform is elevated, the weight of the load is centrally borne by the scissors type supporting leg arrangement. In other words, the entire weight of the load is uniformly applied to the upper ends of the legs I and 4 respectively, and transferred down said legs at opposite sides of the device to the pivotal connections 3 and thence to the lower end portions of said supporting legs.

As the device is raised or lowered, the motor support 21 swings upon the screw, while at the same time maintaining the motor in operative driving relationship to said screw.

Of importance, in this connection, is the fact that although the power is applied to lift the load supporting platform at one end of the apparatus, the downward pressure exerted by the weight ofthe load upon said platform is not assumed by said end only of the apparatus, but isv taken up uniformly and equally throughout the load supporting platform and the supporting means therefor.

In Figs. 4 and 5, there is illustrated another form of the device, including the legs 21 and 23, these being caster mounted and being pivotally connected at 29 and Sil to the load supporting platform 3i having the slot 32 through which passes the pivotal connection 29.

A pallet or skid P, constituting no part of the present invention, is supported upon the platform 3 I, and in turn carries a load of material L.

In this form of the invention a C-shaped motor support 33 supports a motor 3@ driving the chain 35 which in turn rotates the vertical feed screw 3e. The feed screw 35 is journaled at its lower en d in a bearing extension 37 of the support 33 and at its upper end is journaled in the upper end portion of said motor support. Intermediate its ends, the screw has threaded engagement with a threaded bore 38 formed in the rear end of the platform 3i. As a result, when the m-otor is actuated the screw 35 is rotated, and feeds the platform 3| upwardly. As in the previous form of the invention, although the lifting power is applied only at one end of the apparatus, the weight of the load L is borne uniformly and evenly throughout the apparatus.

In the form of the invention illustrated in Figs. 4 and 5, a limit switch 38 comprises an L-shaped arm equipped with the roller 39. The limit switch 38 is pivotally mounted upon the upper end of the support 33 and would be spring urged to a position as seen in Fig. 5. Leads All extend from a suitable source of electric power, not shown, through the switch and leads 4I eX- tend from the switch to the electric motor.

When the load of material L, comprising sheets in the present instance, is so high as to be above the level of the roller 39, the switch will 'be pressed backwardly by the side of the load, as in Fig. 4. In this position the switch is off and the motor will not be actuated. When the load drops to a level which permits the roller 39 to swing forwardly over the top of the load, the switch is moved to the on position actuating the motor and causing elevation of the load platform. The platform is elevated only to an extent as will cause the roller 39 to again be swung to the position of Fig. 4, whereupon the motor will be cut olf. In this way the top level of the load L is kept at a prescribed level of elevation.

In the form of the invention as seen in Figs. 4 and 5, the same characteristics are present as in the nrst form. In other words, the load can overhang three sides of the loading platform, and said loading platform is low-dimensioned on these three sides. Additionally, the lifting power is exert-ed at one end only of the apparatus, but the load weight is absorbed uniformly throughout the area of said apparatus.

Of further importance is the fact that in both cases, the devices are fully portable and selfcontained and can be moved to any desired position for use. In this way, they are readily adaptable for use in warehouses, factories, and at other locations. When used in any location wherein materials have been previously manually handled, they reduce effort and increase efficiency. In other locations, the devices can be used for serving as automatic off bearing devices for machines processing materials in sheet form, and can also be used to feed sheet materials into machines directly fromfloor trucks, skids, and pallets when used with feeding equipment suitable for removing material piece by piece from the top of the load.

In the illustrated modifications, there have been respectively Yshown a screw and toggle lift, and a feed screw lift. However, except as necessarily limited by the claims, I do not desire to limit myself to these particular lifting means, and in my opinion other methods, such as hydraulic and air cylinders, and combinations of these devices with levers, toggles, cams, wedges, cranks, and the like, might well be used. In each instance, however, the device will be characterized by its arrangement wherein the device is made fully portable, wherein load weight is uniformly taken, wherein there is low overall height, and wherein loads of many shapes can be eiliciently handled, including loads that overhang the device on three sides.

What is claimed is:

l. In a load lifter of the type which includes an elongated load supporting platform, a pair of legs adjacent each longitudinal side edge of the platform and one leg of each pair of legs being .asesinar pivotally connected to the platform adjacent one end thereof, the opposite leg of each pair of legs being pivotally and slidably connected to the platform adjacent the opposite end thereof, and the legs of each pair of legs being pivoted together intermediate their ends to move about a common axis, means for moving the legs and raising or lowering the platform comprising toggle links carried by the platform adjacent the end thereof to which the legs are pivoted, said toggle links being connected to the opposite legs, nuts carried by the toggle links, a threaded bar threadedly engaging the nuts for moving the nuts and expanding or collapsing the toggle links, and a prime mover carried by the bar and operatively connected thereto for rotating said bar and moving the nuts.

2. A load lifter comprising spaced parallel pairs of legs, the legs of each pair being pivotally connected together intermediate their ends to move about a common horizontal axis, spaced parallel trunnions carried by the legs and extending longitudinally from the load lifter beyond one end thereof, spaced pairs of convergent toggle links pivotally connected to the trunnions and extending inwardly from opposite sides of the load lifter, and means carried by the toggle links and operatively connected thereto for moving the links about the trunnions and the legs about their pivotal connections.

3. A load lifter which includes an elongated load supporting platform, a pair of legs adjacent each longitudinal side edge of the platform and one leg of each pair of legs being pivotally connected to the platform adjacent one end thereof, the opposite leg of each pair of legs being pivotally and slidably connected to the platform adjacent the opposite end thereof, the legs of each pair of legs being pivoted together intermediate their ends to move about a common axis, a nut carried by the platform adjacent the end thereof to which the legs are pivoted, and means carried by the opposite legs and operatively engaging the nut for raising and lowering the platform and moving the legs about the common axis.

4. A load lifter which includes an elongated load supporting platform, a pair of legs adjacent each longitudinal side edge of the platform and one leg of each pair of legs being pivotally connected to the platform adjacent one end thereof, the opposite leg of each pair of legs being pivotally and slidably connected to the platform adjacent the opposite end thereof, the legs of each pair of legs being pivoted together intermediate their ends to move about a common axis, a nut carried by the platform adjacent the end thereof to which the legs are pivoted, a screw carried by the legs which are pivotally and slidably connected to the platform, said screw being located adjacent the end of the platform to which the legs are pivoted and threadedly engaging the nut,

a prime mover carried by the load lifter adjacent the screw, and means establishing driving connection between the prime mover and the screw.

5. A load lifter which includes an elongated load supporting platform, a pair of legs adjacent each longitudinal side edge of the platform and one leg of each pair of legs being pivotally connected to the platform adjacent one end thereof, the opposite leg of each pair of legs being pivotally and slidably connected to the platform adjacent the opposite end thereof, the legs of each pair of legs being pivoted together intermediate their ends to move about a common axis,

` a frame carried by the legs which are pivotally connected to the platform adjacent one end thereof, the opposite leg of each pair of legs being pivotally and slidably connected to the platform adjacent the opposite end thereof, the legs of each pair of legs being pivoted together intermediate their ends to move about a common axis, a frame carried by the legs which are pivotally and slidably connected to the platform adjacent the ends thereof remote from their pivotal and slidable connection with the platform, a screw mounted in said frame to rotate about a vertical axis, a nut carried by the platform and threadedly engaging the screw, a prime mover carried by the frame and operatively connected with the screw, a limit switch carried by the frame and connected with the prime mover, and an arm carried by and operatively connected to the limit switch for interrupting the flow of electrical energy to the prime mover when a load on the platform exceeds a predetermined height. HAROLD J. HULSART.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 682,083 James Sept. 3, 1901 A1,553,074 Engel Sept. 8, 1925 1,701,314 Shook Feb. 5, 1929 1,941,301 Hanson et al. Dec. 26, 1933 1,986,035 Wells Jan. 1, 1935 1,991,255 Martin Feb. 12, 1935 2,543,296 Meredith Feb. 27, 1951 2,554,494 Hodgin May 29, 1951 

